ITU-T M.732-1989 Signalling and Switching Routine Maintenance Tests and Measurements - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 2 pp
1989ITU-T M.732-1989 Signalling and Switching Routine Maintenance Tests and Measurements - General Maintenance Principles - Maintenance of International Transmission Systems and Telephone Circuits (Study Group IV) 2 pp